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Light-responsive materials

Nanomaterials that release contents on demand hold immense potential to advance biomedical research by enabling scientists to control specific cellular functions far more precisely than is currently possible. Externally triggered release could also be used as a means of targeting drug delivery in the clinic. We’re interested in developing nanomaterials responsive to light because of its excellent spatial and temporal resolution. We take a unique approach to this challenge, designing polymers that degrade into small molecules (rather than simply dissociating from one another) upon irradiation, which means nanoparticles formulated from them should be rapidly cleared from the body and can encapsulate a wider range of cargo than nanoparticles whose light-induced release mechanisms involve heat.

Our first light-degradable material is most sensitive to light in the ultraviolet range, which has potential for application to cultured cells and superficial tissues. In order to provide a material relevant to applications deeper within the body, we substituted the UV-sensitive group in our first polymer with an NIR-sensitive one, which yielded the first NIR-degradable polymer yet created. We're currently working on strategies to enable polymer responsiveness to continuous-wave NIR irradiation (rather than high-energy pulsed, necessary for two-photon absorption). These strategies should broaden the biological applicability of the light-triggered release concept.

NIR-degradable polymer: bromohydroxycoumarin groups are cleaved upon NIR absorption, triggering rearrangements that break the polymer into small molecules.